Type hint for a file or file-like object?
Use either the typing.TextIO or typing.BinaryIO types, for files opened in text mode or binary mode respectively.
From the docs:
class
typing.IOWrapper namespace for I/O stream types.
This defines the generic type
IO[AnyStr]and aliasesTextIOandBinaryIOfor respectivelyIO[str]andIO[bytes]. These representing the types of I/O streams such as returned byopen().
The short answer:
- You need to be explicit. That is
from typing import TextIOnot justfrom typing import *. - Use
IOto mean a file without specifying what kind - Use
TextIOorBinaryIOif you know the type - You cannot currently specify it be opened for write or its encoding.
As an example:
from typing import BinaryIOdef binf(inf: BinaryIO): passwith open('x') as f: binf(f)gives an inspection error (in PyCharm) of Expected type 'BinaryIO', got 'TextIO' instead